Lancet devices are used for taking blood samples by projecting a needle rapidly and momentarily out of the casing so as to prick the skin of a patient. The device needs to have some means of causing the needle to be returned into the casing after it has served its purpose and there is usually a drive spring which, when released, drives the needle forwards, overshooting its static position. It then returns to this position to drive the needle back in the casing. It is an object of this invention to provide spring return means for the lancet which is relatively cheap to manufacture and simple to install, and which removes the need for locating the return spring at the casing and lancet.